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Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward

Helen E. Cockerton, Alayne Street-Perrott Orcid Logo, Philip A. Barker, Melanie J. Leng, Hilary J. Sloane, Katherine Ficken

Quaternary Science Reviews, Volume: 130, Pages: 57 - 71

Swansea University Authors: Alayne Street-Perrott Orcid Logo, Katherine Ficken

DOI (Published version): 10.1016/j.quascirev.2015.07.028

Abstract

On Quaternary time scales, the global biogeochemical cycle of silicon is interlocked with the carbon cycle through biotic enhancement of silicate weathering and uptake of dissolved silica by vascular plants and aquatic microalgae (notably diatoms, for which Si is an essential nutrient). Large tropic...

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Published in: Quaternary Science Reviews
Published: 2015
Online Access: http://dx.doi/org/10.1016/j.quascirev.2015.07.028
URI: https://cronfa.swan.ac.uk/Record/cronfa26978
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spelling 2016-04-25T16:10:54.7766332 v2 26978 2016-03-31 Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward a645a505aeaf6e306126daa6019a9d21 0000-0003-1149-9110 Alayne Street-Perrott Alayne Street-Perrott true false 8f0edd50c22eb16f8e28f23ebc1177b5 Katherine Ficken Katherine Ficken true false 2016-03-31 FGSEN On Quaternary time scales, the global biogeochemical cycle of silicon is interlocked with the carbon cycle through biotic enhancement of silicate weathering and uptake of dissolved silica by vascular plants and aquatic microalgae (notably diatoms, for which Si is an essential nutrient). Large tropical river systems dominate the export of Si from the continents to the oceans. Here, we investigate variations in Si cycling in the upper White Nile basin over the last 15 ka, using sediment cores from Lakes Victoria and Edward. Coupled measurements of stable O and Si isotopes on diatom separates were used to reconstruct past changes in lake hydrology and Si cycling, while the abundances of lipid biomarkers characteristic of terrestrial/emergent higher plants, submerged/floating aquatic macrophytes and freshwater algae document past ecosystem changes. During the late-glacial to mid-Holocene, 15–5.5 ka BP, orbital forcing greatly enhanced monsoon rainfall, forest cover and chemical weathering. Riverine inputs of dissolved silica from the lake catchments exceeded aquatic demand and may also have had lower Si-isotope values. Since 5.5 ka BP, increasingly dry climates and more open vegetation, reinforced by the spread of agricultural cropland over the last 3–4 ka, have reduced dissolved silica inputs into the lakes. Centennial-to millennial-scale dry episodes are also evident in the isotopic records and merit further investigation. Journal Article Quaternary Science Reviews 130 57 71 Late Quaternary; White Nile; Lake Victoria; Lake Edward; Silicon cycle; Diatoms; Oxygen isotopes; Silicon isotopes; Biomarkers 15 12 2015 2015-12-15 10.1016/j.quascirev.2015.07.028 http://dx.doi/org/10.1016/j.quascirev.2015.07.028 Gold Open Access. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). COLLEGE NANME Science and Engineering - Faculty COLLEGE CODE FGSEN Swansea University RCUK 2016-04-25T16:10:54.7766332 2016-03-31T12:07:56.2004167 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Geography Helen E. Cockerton 1 Alayne Street-Perrott 0000-0003-1149-9110 2 Philip A. Barker 3 Melanie J. Leng 4 Hilary J. Sloane 5 Katherine Ficken 6 0026978-31032016121940.pdf 1-s2.0-S0277379115300664-main.pdf 2016-03-31T12:19:40.0070000 Output 2815782 application/pdf Version of Record true 2016-04-25T00:00:00.0000000 true
title Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
spellingShingle Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
Alayne Street-Perrott
Katherine Ficken
title_short Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
title_full Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
title_fullStr Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
title_full_unstemmed Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
title_sort Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
author_id_str_mv a645a505aeaf6e306126daa6019a9d21
8f0edd50c22eb16f8e28f23ebc1177b5
author_id_fullname_str_mv a645a505aeaf6e306126daa6019a9d21_***_Alayne Street-Perrott
8f0edd50c22eb16f8e28f23ebc1177b5_***_Katherine Ficken
author Alayne Street-Perrott
Katherine Ficken
author2 Helen E. Cockerton
Alayne Street-Perrott
Philip A. Barker
Melanie J. Leng
Hilary J. Sloane
Katherine Ficken
format Journal article
container_title Quaternary Science Reviews
container_volume 130
container_start_page 57
publishDate 2015
institution Swansea University
doi_str_mv 10.1016/j.quascirev.2015.07.028
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Geography{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Geography
url http://dx.doi/org/10.1016/j.quascirev.2015.07.028
document_store_str 1
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description On Quaternary time scales, the global biogeochemical cycle of silicon is interlocked with the carbon cycle through biotic enhancement of silicate weathering and uptake of dissolved silica by vascular plants and aquatic microalgae (notably diatoms, for which Si is an essential nutrient). Large tropical river systems dominate the export of Si from the continents to the oceans. Here, we investigate variations in Si cycling in the upper White Nile basin over the last 15 ka, using sediment cores from Lakes Victoria and Edward. Coupled measurements of stable O and Si isotopes on diatom separates were used to reconstruct past changes in lake hydrology and Si cycling, while the abundances of lipid biomarkers characteristic of terrestrial/emergent higher plants, submerged/floating aquatic macrophytes and freshwater algae document past ecosystem changes. During the late-glacial to mid-Holocene, 15–5.5 ka BP, orbital forcing greatly enhanced monsoon rainfall, forest cover and chemical weathering. Riverine inputs of dissolved silica from the lake catchments exceeded aquatic demand and may also have had lower Si-isotope values. Since 5.5 ka BP, increasingly dry climates and more open vegetation, reinforced by the spread of agricultural cropland over the last 3–4 ka, have reduced dissolved silica inputs into the lakes. Centennial-to millennial-scale dry episodes are also evident in the isotopic records and merit further investigation.
published_date 2015-12-15T03:32:35Z
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